Holograms and other light diffraction sheets have been known in the art for some time. They are currently employed in a wide variety of applications including display advertising, greeting cards, die-cut letters and anticounterfeiting. In such applications, holograms are mounted as unitary sheets to materials such as cardboard, plastic and metals.
Attempts have been made to incorporate this visually stimulating technology into flexible materials such as textiles and the like. However, current techniques for applying holograms to flexible materials have been found to suffer from significantly limited flexibility in the end product.
For example, current methods for attaching holograms to textiles are illustrated in U.S. Pat. Nos. 4,838,965 and 4,956,040 wherein the hologram sheets are adhered to the fabric as a continuous sheet, with a thick layer of adhesive applied across the entire hologram-fabric interface. The flexibility of the fabric at the location of the hologram is thereby significantly reduced and the image is subject to cracking upon fairly minimal flexing of the fabric. Thus, there is a need for an improved method of affixing light diffracting sheets such as holograms to flexible materials which does not significantly limit the flexibility of the end product.
Furthermore, it is the striking visual image of holograms which makes the use of such materials on textiles so desirable. Therefore, it is important that the upper surface of the hologram or diffraction grating be as freely exposed as possible, with minimal materials covering any portion thereof. Current methods for attaching such images to textiles, as illustrated in the aforementioned U.S. Pat. Nos. 4,838,965 and 4,956,040, provide for at least the entire perimeter of the upper surface of the hologram to be covered with material of significant thickness, or the entire upper surface to be covered with a material of significant thickness in the process of adhering the hologram to the textile. Accordingly, there is a need for a method of attaching holograms which leaves the upper surface of the hologram as clear as possible, to take advantage of the full visual effect associated therewith.
Moreover, there is a need for such a product which allows for laundering of the fabric to which a light diffracting image has been applied, together with the image formed thereon, which allows for subsequent launderings of the composite without significant loss of the quality of the stimulating visual effect of the applied light diffracting image. More specifically, there is a need for such a washable composite which allows for formation of a limitless variety of light diffracting designs, yet still provides significant flexibility of the washable composite without deterioration of the applied image.
The process and apparatus for carrying out the process should lend themselves to simple and economical manufacture. In this regard, it is desirable that the method and apparatus for applying the light diffracting images take advantage of existing apparatus already commonly employed in the application of images to fabrics.